User interface for a portion of a display screen



The FIGURE is a front view of a user interface for a portion of a display screen showing our new design.

The broken line drawings of a portion of a display screen, the interior rectangle, the upper right and lower right rectangles, and the small elements on the bottom edge are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a user interface for a portion of a display screen, as shown and described. 